Apparatus for producing a vacuum in a test tube

ABSTRACT

Apparatus is provided for forming a vacuum in a test tube in the field. A cap is mounted on an insertion tool by having a projection on the tool cam out a detent on the cap as it passes. The cap is then rammed into a test tube by use of the tool, a flange on the cap bending back to permit air to escape. With the whole cap in the tube, the detent is prevented from being cammed out, permitting the tool to be used to withdraw the cap from the tube. As the cap is withdrawn, the flange is forced against the walls of the tube to prevent air reentering the tube. When the upper portion of the cap leaves the tube, the detent is again cammed out by the projection on the tool, releasing the tool. The lower portion of the cap, including the flange, remains in the tube to seal it.

United States Patent [191 Green 1451 May 27, 1975 [76] lnventor: DavidThomas Green, Wolfpit Ave.,

Norwalk, Conn. 06851 [22] Filed: May 29, 1974 211 Appl. No.:474,236

Related US. Application Data [63] Continuation of Ser. No. 266,396, June26, 1972,

abandoned.

[52] US. Cl. 128/2 F; 128/D1G. 5; 128/220; 128/276; 128/278 [51] Int.Cl. A6lb 5/14; A61m H00 [58] Field of Search 128/2 F, DIG. 5, 275, 276,128/278, 220, 218 P, 218 D; 215/47; 417/566 3,378,008 4/1968 Ogle128/220 3,645,253 2/1972 Goverde et a1. 128/2 F 3,696,806 10/1972 Sausse128/2 F Primary Examiner-Kyle L. Howell Attorney, Agent, or Firm-JosephLevinson, Esq.

1 1 ABSTRACT Apparatus is provided for forming a vacuum in a test tubein the field. A cap is mounted on an insertion tool by having aprojection on the tool cam out a detent on the cap as it passes. The capis then rammed into a test tube by use of the tool, a flange on the capbending back to permit air to escape. With the whole cap in the tube,the detent is prevented from being cammed out, permitting the tool to beused to withdraw the cap from the tube. As the cap is withdrawn, theflange is forced against the walls of the tube to prevent air reenteringthe tube. When the upper portion of the cap leaves the tube, the detentis again cammed out by the projection on the tool, releasing the tool.

The lower portion of the cap, including the flange, remains in the tubeto seal it.

7 Claims, 6 Drawing Figures APPARATUS FOR PRODUCING A VACUUM IN A TESTTUBE RELATED APPLICATIONS This application is a continuation of myearlier copending application, Ser. No. 266,396, filed June 26, 1972,and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to apparatus forcreating a vacuum in a test tube and more particularly to such anapparatus which permits tests tubes to be vacuumized in the fieldwithout requiring complex or expensive equipment.

For many years sealed, vacuumized test tubes have been sold tohospitals, doctors, and other medical organizations for use in drawingblood and other biological samples. Vacuumized tubes have been foundpreferable for these applications over standard hypodermic needles orsyringes for at least two reasons. First, when a hypodermic needle isutilized to draw blood from a vein, there is a possibility that acareless attendant might accidentally depress the plunger while theneedle is in the vein, injecting air into the vein. Air inadvertentlyinjected into an individuals veins could result in a fatal stroke orembolism. Secondly, depressing the hypodermic plunger to remove bloodtherefrom may break up or otherwise damage corpuscles in the blood,introducing the possibility of inaccurate test results. Similar problemsmay exist when a hypodermic needle is utilized to draw other biologicalsamples.

While the prevacuumized test tubes presently available overcome theproblems indicated above, and have thus enjoyed substantial commercialsuccess, they do present certain problems. First, while the cost ofcleaning the tubes after use is relatively low, the cost of shipping thetubes back to the manufacturer after use to be revacuumized is highenough so that this procedure is not economically feasible. Thus, mostof the tubes are now thrown away after a single use. Second, relativelyexpensive rubber caps must be used rather than plastic caps to seal thetubes. This requirement exists because plastic is slightly porous, andthe shelf life of a vacuumized tube with a plastic cap would thus beminimal.

From the above it is apparent that the cost of utilizing vacuumized testtubes could be substantially reduced if a procedure could be providedfor permitting the tubes to be revacuumized at the site. Further, if therevacuumizing could be accomplished within a short time before use (forexample within a day or two before use) relatively inexpensive plasticsealing caps could be substituted for the rubber caps now utilized.

An additional problem which could be solved by providing a capability ofvacuumizing test tubes at the site is that of storing cultures which canbreed only in a vacuum. At present, expensive equipment is required atfacilities working with these cultures.

Another shortcoming of existing pre-vacuumized test tubes is that, wherea substance such as an anticoagulant is required to be mixed with thebiological sample applied to the tube, the substance is normally placedin the tube before it is vacuumized and sits in the bottom of the tubewhen the sample flows in. When a tube is filled, the attendant mustshake the tube to insure proper mixing of the substance with the sample.Should the attendant inadvertently forget to shake the tube after thesample is drawn,'damage to the sample may occur. Further, certainsubstances are of a type which may not be stored in a vacuum, and themixing of these samples presents special problems with existingprevacummized tubes. A requirement therefore exists for a procedure topermit the storage of substances to be mixed with a biological sampleunder nonvacuum conditions and in a manner so as to insure substantialmixing of the substance and the sample.

SUMMARY OF THE INVENTION In view of the above, this invention providesan apparatus for forming a vacuum in a test tube and of sealing thetube. The apparatus involves the use of a cap which is adaptable 'foruse with a simple insertion tool. The cap consists of a body formed of acylindrically shaped upper portion and an enlarged cylindrically shapedlower portion with the diameter of the lower portion being less thanthat of the test tube to be vacuumized. The upper portion of the cap issealed at its top and has an internal bore which terminates in anenlarged counterbore in the lower portion. A flexible flange ring isformed as an integral part of the base of the lower portion, thediameter of the flange being greater than the test tube diameter. Adetent means is mounted on the upper portion of the body, the detentmeans being shaped and positioned to be cammed out of the way of the capinsertion tool to permit the tool to be passed in or out of the cap whenthe upper portion of the cap is out of the test tube. However, when theupper portion of the cap is in the test tube, the walls of the test tubeinhibit the camming out of the detent means. Thus, the insertion tool isheld in the cap by the detent means so long as the upper portion of thecap is in the test tube. This permits the cap to be lowered into thetest tube by the tool, with air escaping around the flange ring as thisis done. The tool is then used to draw the cap out of the tube, theflange coacting with the walls of the tube to form a seal to prevent airfrom reentering the tube.

When the upper portion of the cap is out of the tube,

the tool is released, the lower portion of the cap and the flangeremaining in the tube to form a vacuum seal.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention as illustrated inthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of thesealing cap and insertion tool of a. preferred embodiment of theinvention.

FIG. 2 is a cutaway side view along the line of a 2-2 of FIG. '1 of acap and a portion of the insertion tool of the preferred embodiment ofthe invention.

FIG. 3 is a partially cutaway sideview showing the cap partially mountedon the insertion tool.

FIG. 4 is a partially cutaway side view illustrating the cap fullymounted on the tool. and inserted in the test tube.

FIG. 5 is a partially cutaway side view illustrating the cap sealing thetube with the insertion tool released.

FIG. 6 is a partially cutaway sideview illustrating the vacuumized testtube with the cap mounted on a needle assembly and being utilized fordrawing a biological sample.

DETAILED DESCRIPTION Referring now to the figures, it is seen that thisinvention includes a test tube sealing cap and a cap insertion tool 12.The body of the cap is formed of an upper cylindrical portion 14 and alower cylindrical portion 16 of enlarged diameter. Portion 14 has a bore18 which terminates at one end in an enlarged counterbore 20 in portion16 and is sealed at the other end by the top of the cap 22. The diameterof enlarged portion 16 of the cap is slightly less than the diameter oftest tube 24 with which the cap is to be utilized.

A flexible flange ring 26 is formed as an integral part of and projectsfrom the lower end of enlarged portion 16. The lower surface 28 of ring26 is preferably ridged for reasons which will be described shortly. Anannular groove 30 is formed in portion 16 just above flange 26. As willbe seen shortly, flange 26 may be bent back into groove 30 when the capis inserted in test tube 24.

A pair of webs 32 project from opposite sides of upper portion 14 of cap10. As may be best seen in FIG. 2, the depth of the web is greater atthe bottom of the web than at the top. Similarly the width of the webmay also be greater at the bottom. Projecting from the bottom of eachweb 32 is a cantilevered detent arm 34 at the end of which is mounted adetent 36 having a triangular cross section. Each detent 36 has atapered leading edge 36 and a tapered trailing edge 40.

Another feature of cap 10 is a ring-shaped groove 42 formed in the uppersurface of lower portion 16. An optional feature of cap 10 is arupturable seal 44 across the lower end of bore 18. An anticoagulant orother substance may be sealed in bore 18 by sea] 44. While cap 10 may beconstructed of rubber, for reasons of cost and ease of fabrication it ispreferably formed of a plastic. Seal 44 may be formed of a suitablematerial such as an, elastomer.

Tool 12 consists of a handle 46, a shank 48, and a head 50. Head 50consists of a pair of cantilevered arms 52 which are spaced at theirends by a distance slightly greater than the width of a web 32. Arms 52may be formed by cutting a pair of grooves 54 in a short cylindricaltube. A projection 56 having a triangular cross-section-with an angledleading edge 58 and an angled trailing edge 60 is formed at each end ofeach arm 52 adjacent to slots 54. The length of each arm 52 is slightlygreater than the height of upper portion 14 of cap 10.

Operation In operation, a cap 10 is first fitted onto a tool 12. This isaccomplished by inserting the upper portion 14 of the cap into thehollow center of the head 50 with webs 32 being positioned in grooves54. When the leading edges 58 of projections 56 come into contact withthe leading edges 38 of detents 36, angled edges 38 and v 58 coact tocam projections 36 out of the way of projections 56. FIG. '3 illustratesthe cap and the tool in this partially assembled condition. As cap 10 ismoved further into the head of tool 12, projections 56 pass detents 36and come to rest positioned partially in groove 42. The naturalresiliency of the plastic material of arms 34 causes the arms 34 anddetents 36 to return to substantially their initial position onceprojections 56 have passed. FIG. 4 illustrates the relative position ofthe cap and tool when they are fully mated. When cap 10 is mounted ontotool 12, the attendant uses the tool to insert the cap into the mouth oftest tube 24 and to push the cap all the way to the bottom of the tube.FIG. 4 illustrates the arrangement of the various elements with cap 10inserted all the way into tube 24. It is noted that since flange ring 26has a diameter greater than that of the test tube, it is folded back toa position partially into groove 30 when the cap is in the test tube. Asthe cap is inserted into the tube, the pressure of the air trapped aheadof the cap presses against flange 26 forcing flange 26 out of contactwith the walls of tube 24 and further into groove 30. Since the diameterof the remainder of cap 10 is slightly smaller than the diameter of thetest tube, air ahead of the cap is permitted to escape as the cap isinserted into the tube. Thus with cap 10 all the way into the tube, asshown in FIG. 4, there is virtually no air remaining in the portion ofthe tube under the cap.

The next step in the operation is to withdraw cap 10 from the tube,again, using tool 12 for this purpose. When a force is initially appliedto tool 12 in a direction to remove the tool from tube 24, the toolmoves relative to the cap until trailing edges 40 and 60 engage. Sincethese surfaces are both angled, the interaction of the surfaces has atendency to cam detent 36 out of the way of projections 56. However, asseen in FIG. 4, the walls of tube 24 are in close proximity to arms 34and detents 36, preventing them from being cammed out to the positionsshown in FIG. 3. Cap 10 is thus held in tool 12 by the interaction ofdetent 36 with projections 56, permitting the tool to be utilized todraw the cap out of tube 24. As cap 10 is withdrawn from tube 24, thereduced pressure remaining in the area of the tube under the cap drawsflange 26 down into the tube. This action is opposed by the walls oftube 24. The pressure differential between the front and back of flange26 is thus effective at this time to force the flange against the wallsof the tube, providing a seal that prevents air from leaking back intothe area of the tube under the cap. Ridges 28 on the underside of flange26 provide a larger contacting area between the flange and the tube,improving the sealing action. A substantial vacuum therefore remains intube 24 in the portion thereof under cap 10.

When cap 10 has been removed to the position shown in FIG. 5, with itsupper portion 14 out of tube 24, arms 34 and detents 36 are no longerrestrained by the walls of tube 24 and are cammed out to permit thepassage of projections 56. Cap 10 is thus, at this stage of theoperation, removed from tool 12. As detents 36 are cammed out, theyfrictionally engage the upper edge of tube 24. This frictionalengagement holds the detents in the position shown in FIG. 5, where theycoact with the upper surface of the tube to prevent the cap from beingdrawn back into the tube.

From the above it is apparent that a three-step operation has beenprovided for vacuumizing a test tube. The operation may be performedrapidly, normally in a matter of seconds, by a minimally trainedindividual utilizing simple and inexpensive equipment.

FIG. 6 illustrates a vacuumized test tube 24 sealed with a cap 10 as itis utilized for drawing a biological sample. For this operation, one endof a hollow needle 64 is inserted into, for example, a vein of theindividual from whom a biological sample is to be drawn. Needle 64 ismounted and sealed in a cup-shaped holder 66 which may, for example, beconstructed of glass or a plastic material. The capped end of tube 24 isinserted into holder 66 to a position where the other end of needle 64pierces end 22 of cap 10. When this occurs, the pressure differentialbetween, for example, the vein at one end of needle 64 and the vacuum atthe other end of needle 64 causes the blood or other biological sampleto flow through needle 64 into tube 24. Fluid continues to flow throughneedle 64 until the pressure at its two ends has been equalized. If thetube has been properly evacuated, this will occur when tube 24 has beensubstantially filled. When tube 24 is full, needle 64 is removed fromthe individual and tube 24, with cap still in place, removed from theholder and needle assembly. The hole made in cap 10 by needle 64 willnormally seal adequately to permit the sample to be stored and shippedin the tube.

If there is a substance to be mixed with the sample stored in bore 18behind seal 44, the increased pressure differential across seal 44 whenneedle 64 pierces the cap will rupture the seal, permitting thesubstance and the sample to flow together into tube 24. Since the sampleflows through the substance on entering the tube, and the two elementsenter the tube together, a good mixing action is effected, eliminatingthe need for subsequent shaking by the attendant. Should a seal 44 berequired which is strong enough so as not to be rupturable by thepressure differential created when the needle enters cap 10, the lengthof bore 18 and of the needle may be selected so that the needlepenetrates seal 44 causing it to rupture.

While in the description above, it has been assumed that the tube 24 isempty when it is vacuumized, it is apparent that a culture or othersubstance to be stored in vacuum could be in the tube at that timeFurther, while a particular detent mechanism-36 and means for mountingit has been shown, it is apparent that all that is required is that adetent mechanism be provided which may be cammed out of the way of asuitably designed insertion tool when the upper portion of the cap bodyis out of the tube but is restrained from being cammed when the upperportion of the cap is in the tube. Thus, while the invention has beenparticularly shown and described above with reference to'a preferredembodiment thereof, it will be apparent to those skilled in the art thatthe foregoing and other changes in form and details may be made thereinby those skilled in the art without departing from the spirit and scopeof the invention.

What is claimed is:

1. A device for forming a vacuum in a test tube when inserted, movedalong the length therein and then partially withdrawn therefrom, thepartial withdrawal sealing the test tube to maintain the vacuum producedtherein, comprising a. a test tube which is desired to be evacuatedhaving walls therein,

b. a cap on said test tube having an integral body formed of acylindrically shaped upper portion sealed on one end thereof, and anenlarged cylindrically shaped lower portion of diameter less than thatof said test tube, whereby said cap may be inserted, moved therein, andpartially withdrawn from said test tube,

c. a flexible flange ring formed as an integral part of said lowerportion, the diameter of said flange being greater than the diameter ofsaid test tube, said flexible flange being lbent back on said lowerportion of said body when said cap is inserted and moved along thelength of said test tube, the pressure of air trapped ahead of said capforcing said flexible flange ring out of contact with the walls of saidtest tube, allowing the trapped air to escape between the walls of saidtest tube and the smaller diameter of said integral body, said flexibleflange contacting the walls of said test tube as said cap is partiallywithdrawn thereform to maintain the vacuum in said testtube below saidcap,

d. an insertion tool having detachable mounting means positioned on oneend thereof engaging said cap and moving said cap in said test tube, and

e. flexible detent means mounted on said upper portion of said bodyengaging said detachable mounting means of said insertion tool, saiddetent means and said detachable mounting means defining means wherebysaid insertion tool remains mounted on said cap so long as the walls ofsaid test tube are in contact with said flexible detent means, saidflexible detent means releases said insertion tool from said cap whensaid upper portion of said cap is removed from said test tube, saidflexible detent means being deflected by said detachable mounting meanson removal from said test tube, thereby gripping the top of said testtube by said cap to prevent said cap from moving back into said testtube which has been evacuated thereby.

2. A device as claimed in claim 1 wherein said flexible detent meanscomprise a. pair of flexible detent means each mounted on a webextending from said upper portion of said body.

3. A device as claimed in claim 2 wherein each of said flexible detentmeans includes a cantilever arm extending from the corresponding webwith a projection having angled forward and trailing edges mounted atthe end of said cantilever arm.

4. The device claimed in claim 3 wherein said insertion tool comprises arod terminating in a pair of cantilever arms spaced sufficiently topermit said webs of said body to pass between said arms, and at leastone projection having angled forward and trailing edges mounted at theend of each arm adapted to deform said flexible detent means therebypositioning said rod on said cap.

5. A device as claimed in claim 1 wherein said flexible flange ring hasa ridged lower surface thereon.

6. A device as claimed in claim 1 including an annular groove formed insaid lower portion just above said flexible flange ring, said groovereceiving said flexible flange ring when said cap is being inserted andmoved in the test tube to permit air to pass said flexible flange ring.

7. A device as claimed in claim 1 including a bore formed from said sealin said upper portion through the remainder of said cap, and including arupturable seal formed across said bore at a point along the lengththereof, and a substance which is desired to be mixed with a fluid whichmay be applied to said test tube being stored in said bore above saidseal.

1. A device for forming a vacuum in a test tube when inserted, movedalong the length therein and then partially withdrawn therefrom, thepartial withdrawal sealing the test tube to maintain the vacuum producedtherein, comprising a. a test tube which is desired to be evacuatedhaving walls therein, b. a cap on said test tube having an integral bodyformed of a cylindrically shaped upper portion sealed on one endthereof, and an enlarged cylindrically shaped lower portion of diameterless than that of said test tube, whereby said cap may be inserted,moved therein, and partially withdrawn from said test tube, c. aflexible flange ring formed as an integral part of said lower portion,the diameter of said flange being greater than the diameter of said testtube, said flexible flange being bent back on said lower portion of saidbody when said cap is inserted and moved along the length of said testtube, the pressure of air trapped ahead of said cap forcing saidflexible flange ring out of contact with the walls of said test tube,allowing the trapped air to escape between the walls of said test tubeand the smaller diameter of said integral body, said flexible flangecontacting the walls of said test tube as said cap is partiallywithdrawn thereform to maintain the vacuum in said test tube below saidcap, d. an insertion tool having detachable mounting means positioned onone end thereof engaging said cap and moving said cap in said test tube,and e. flexible detent means mounted on said upper portion of said bodyengaging said detachable mounting means of said insertion tool, saiddetent means and said detachable mounting means defining means wherebysaid insertion tool remains mounted on said cap so long as the walls ofsaid test tube are in contact with said flexible detent means, saidflexible detent means releases said insertion tool from said cap whensaid upper portion of said cap is removed from said test tube, saidflexible detent means being deflected by said detachable mounting meanson removal from said test tube, thereby gripping the top of said testtube by said cap to prevent said cap from moving back into said testtube which has been evacuated thereby.
 2. A device as claimed in claim 1wherein said flexible detent means comprise a pair of flexible detentmeans each mounted on a web extending from said upper portion of saidbody.
 3. A device as claimed in claim 2 wherein each of said flexibledetent means includes a cantilever arm extending from the correspondingweb with a projection having angled forward and trailing edges mountedat the end of said cantilever arm.
 4. The device claimed in claim 3wherein said insertion tool comprises a rod terminating in a pair ofcantilever arms spaced sufficiently to permit said webs of said body topass between said arms, and at least one projection having angledforward and trailing edges mounted at the end of each arm adapted todeform said flexible detent means thereby positioning said rod on saidcap.
 5. A device as claimed in claim 1 wherein said flexible flange ringhas a ridged lower surface thereon.
 6. A device as claimed in claim 1including an annular groove formed in said lower portion just above saidflexible flange ring, said groove receiving said flexible flange ringwhen said cap is being inserted and moved in the test tube to permit airto pass said flexible flange ring.
 7. A device as claimed in claim 1including a bore formed from said seal in said upper portion through theremainder of said cap, and including a rupturable seal formed acrosssaid bore at a point along the length thereof, and a substance which isdesired to be mixed with a fluid which may be applied to said test tubebeing stored in said bore above said seal.